Types Of Twins Research Articles

A systematic study of disclination-induced internal stress associated with multiple types of twin-twin reactions in Mg alloys: analytical solutions and numerical calculations

Deformation twinning plays an important role in enhancing the mechanical properties of metals and alloys by mechanisms such as twinning-induced plasticity and strain hardening. However, internal stress concentration associated with the interactions and reactions of twins may also lead to the degradation of ductility and fracture toughness. While the elastic behavior of individual twin types has been extensively studied, the crystallographic reactions among multiple types of twins have not been well recognized, which could produce high-index or irrational twins as well as byproduct disclinations. A theoretical framework to predict twin-twin reaction products and quantify associated internal stress is still unavailable. Here we suggest a general approach to investigate twin-twin reactions through symmetry-dictated characteristic defect analyses and stress field calculations based on disclination theory. By using Mg as an example, a systematic study of multiple types of twin-twin reactions has been conducted. The product defects arising from the reactions and associated internal stress fields have been determined analytically, which are validated by numerical simulations and experimental measurements. This work not only establishes a theoretical foundation for quantifying defect-induced internal stress concentration from complicated twin-twin interactions/reactions, but also offers new insights into the impact of deformation twins on mechanical properties.

Deformation Behavior and Microstructural Evolution Coordinated Regulation by Compression Deformation for Metastable Ti Alloy.

In this paper, in order to investigate the harmonious relationship between the compression deformation behavior of metastable β titanium alloy and the microstructure evolution, the β solution-treated Ti-10V-2Fe-3Al (Ti-1023) alloy was compressed at room temperature and its deformation behavior was analyzed. Optical microscopy (OM) and field emission electron microscopy (FESEM) were used to study the microstructure evolution of alloys at different strain rates. The results show that the stress-induced martensite transformation (SIMT) is more easily activated by low strain rate compression deformation, which is conducive to improving its comprehensive mechanical properties. With the decrease in strain rate, the α″ martensite content increases significantly, the average grain size decreases substantially, and the Low Angle Grain Boundary (LAGB) volume fraction decreases correspondingly. In addition, after compression at different strain rates, the misorientation angle (MA) of the β matrix is mainly concentrated in the LAGBs. The change is small with the decrease in strain rate, but the α″ martensite orientation difference angle shows some peaks, which are ~60°, ~85°, and ~95°, respectively. Simultaneously, the strain rate has an important effect on the content and type of martensitic twins. Finally, the fracture morphology analysis shows that with the increase in strain rate, the fracture mode changes from ductile fracture to brittle fracture. The fracture surface presents a significantly elongated cavity along the direction of maximum shear stress.

Varying the holding time to modify microstructure and improve forming angle precision of AZ31 magnesium sheet

An effective method to precisely control sheet metal forming is proposed by varying the holding time. To clarify the differences in forming angles under different holding times, this study conducted 90° precision forming experiments on AZ31 magnesium sheets using two methods: a holding time of 5 seconds ( HT5S) and a holding time of 1 hour ( HT1H). The grain size and recrystallization, twinning and texture, Schmidt factor on the tension and compression sides of the bending fillet were all investigated using an optical microscope and EBSD technology, and the mechanism causing the difference in forming angle was defined. The results show: on both sides of tension and compression, grain size and recrystallized structure, high or low angle grain boundaries, the proportion of different types of twins, texture strength and Schmidt factor all changed in order to coordinate plastic deformation. When the forming method is switched from HT5S to HT1H, the forming angle is close to the target value, and the average value decreases by 2.734 %. But it also raises the risk of failure. Among them, after the proportion of {10−12} twins and the Schmidt factor of the {0001} basal slip system decrease, more twins and slip systems need to be activated to coordinate plastic forming. The activation of twins and slip systems requires greater stress, which can easily lead to uncoordinated plastic deformation and failure.

Twin embryo formation by induced parthenogenesis.

Induction of parthenogenesis (embryo formation from unfertilized egg cells) by embryogenic transcription factors is associated with twin formation at high frequencies, and involves two distinct mechanisms. Synthetic apomixis has been achieved through the induction of parthenogenesis by ectopic expression of the Baby Boom family of transcription factors. An associated phenomenon from this process is the formation of polyembryony including twin progeny at high frequencies, but the underlying mechanisms have not been explored. Here, we provide a brief description of the phenomenon, discuss potential mechanisms for twin formation in flowering plants, propose two possible models for their occurrence, and evaluate the available evidence from both dizygotic and monozygotic twins in relation to these models. The two proposed models are independent, but they can operate in combination. We conclude that both models are required to explain the types of twins and triplets that we and others have observed. These models provide future directions for basic research, as well as suggest possible approaches towards reducing polyembryony when incorporating synthetic apomixis into crop plants such as maize where twinning is not desirable.

Mechanism of shape memory effect alteration in Ni50.4Ti49.6 via laser powder bed fusion from the perspective of martensitic twin

ABSTRACT The phase transformation from martensitic twins to austenite phase in NiTi shape memory alloys (SMAs) determines their shape memory effect (SME). However, systematic studies are indeed needed to reveal which martensitic twin type is effective in enhancing the SME for NiTi SMAs due to the diversity of martensitic twins. In this work, based on laser powder bed fusion (LPBF) NiTi SMAs, an excellent strength-ductility combination of 900.5 MPa and 13.9% was obtained by utilising a low laser power (70 W) and scanning speed (200 mm/s), which represents one of the highest values attainable among current LPBF NiTi SMAs. Furthermore, based on transmission kikuchi diffraction, it is found that high-density { 11 1 ¯ } I-type martensitic twins enhanced the SME of LPBF NiTi SMAs significantly, and the maximum SME recovery ratio is 95.8% after 10 cycles at controlled strain (6%) cyclic tensile loading-unloading. Conversely, the formation of { 1 ¯ 11 } I-type martensitic twins in the matrix weakened the SME of LPBF NiTi SMAs remarkably and lost SME after 10 cycles at controlled strain (6%) cyclic tensile loading-unloading. This research offers some valuable insights into the relationship between martensitic twin and SME for LPBF NiTi SMAs and paves the new way for modulation of microstructure to enhance mechanical properties and SME for NiTi SMAs via LPBF.

Digital Twin Types and Applications in Healthcare.

Digital Twins, represents an innovative approach consisting of real-time digital replicas of physical entities. This innovative concept has already many applications in Industry, automotive, business environment and is also transforming the healthcare industry. Digital Twins have the potential to provide comprehensive models of individual patients, hospital facilities, and medical processes, integrating data from various sources such as electronic health records, wearable devices, and imaging systems. This paper discusses Digital Twin models and their application in healthcare, focusing on care coordination, treatment planning and hospital management development.

Architecting a digital twin for wind turbine rotor blade aerodynamic monitoring

Digital twins play an ever-increasing role in maximising the value of measurement and synthetic data by providing real-time monitoring of physical systems, integrating predictive models and creating actionable insights. This paper presents the development and implementation of the Aerosense digital twin for aerodynamic monitoring of wind turbine rotor blades. Employing low-cost, easy-to-install microelectromechanical (MEMS) sensors, the Aerosense system collects aerodynamic and acoustic data from rotor blades. This data is analysed through a cloud-based system that enables real-time analytics and predictive modelling. Our methodological approach frames digital twin development as a systems engineering problem and utilises design patterns, design thinking, and a co-design framework from applied category theory to aid in the development process. The paper details the architecture, deployment, and validation of a ‘Digital Shadow’-type twin with simulation/prediction functionalities. The solution pattern is discussed in terms of its implementation challenges and broader applicability. By providing a practical solution to integrating all the digital twin components into a holistic system, we aim to help wind energy specialists learn how to transform a conceptual idea of a digital twin into a functional implementation for any application.

Rules to identify and track the evolution dynamics of [formula omitted] twin variants in hexagonal close-packed metals

Twinning evolution laws derived based on physics are required to model plasticity and texture evolution resulting from the twinning in hexagonal close-packed structures. Atomistic simulations are employed to study the evolution of {101̄2} twins in Ti at 5 K temperature. The misorientation angle between the twinned region and parent matrix differs from the expected misorientation angle of 85.03∘. This closely aligns with the experimental findings. The deviation of twinning from {101̄2} twin plane makes it difficult to identify conjugate twins, leading to their coalescence. Both the c-vector and disorientation angle analyses are unable to track the variant type of the conjugate twins. The disorientation angle analysis can identify the conjugate twin variants but is unable to identify the variant type of the twin. The c-vector analysis can identify the conjugate twin variants as well as the variant type of the twin but is unable to track the variant type of the twin during its evolution. A set of rules are proposed to track the variant type of the twin during its evolution. These rules should help to understand the twin evolution dynamics in HCP metals and can be applied to study the twinning evolution dynamics at ambient conditions, even though they are designed for twinning evolution at 5 K temperature. The fundamental understanding of twin evolution dynamics should motivate the construction of the physics-based evolution laws for twinning.

Research on the Application of Digital Twin Technology in Equipment Maintenance

Digital twin technology is to make full use of the data such as physical model, sensor update, running history, integrate the multi-subject multi-physical quantity, multi-scale, multi-probability simulation process, complete the mapping in virtual space, thus reflect the whole life cycle process of the corresponding entity equipment. In this paper, the digital twin of a certain type of equipment system is studied to realize the operation condition monitoring, fault intelligent diagnosis and so on, so as to improve the maintenance efficiency and effect of the equipment.

Pressure loss and droplet entrainment under spray absorber conditions

The interaction of spray with counter-flowing flue gas causes pressure loss (ΔP) and influences droplet entrainment and sorbent loss in gas–liquid scrubbers. As these phenomena were usually investigated separately and not linked with atomizer characteristics, it is difficult to obtain insight into the scrubber operation and select an atomization device proper to particular process. Atomizers typically used in a spray column, together with pressure-swirl and twin fluid effervescent types, were tested in column-like conditions. All the atomizers were tested at the same liquid flow rate of 140 kg/h, with inlet pressure (pin) from 0.025 to 0.2 MPa under the counter–flow velocity (ucf) ranging from 0to1 m/s. A small-scale low-speed wind tunnel was specially designed to simulate spray column flow conditions. The ΔP and droplet entrainment were correlated with atomizer operating regimes. Empirical and analytical models of ΔP were compared with experimental results for different atomizers. Limitations of both models are discussed. The ΔP is influenced by the spray velocity at the discharge orifice (uL) and correlates well with the liquid kinetic energy (Ek) and Reynolds number at the discharge orifice. The atomizers working on higher pin, provide a larger interfacial area, but yield higher Ek at the discharge orifice, causing larger ΔP and a greater risk of sorbent loss due to presence of smaller droplets.

Magnetic field-assisted electrochemical additive manufacturing of nickel structure: Growth mechanism and microstructural evolution

The microstructure and crystal texture of magnetically assisted electrochemical additive manufacturing parts play crucial roles in their mechanical properties and applications. This paper elucidates the electrocrystallization process of electrochemical additive manufacturing by constructing a magnetically assisted setup and exploring both nucleation mechanisms and growth kinetics. The electrochemical behavior of the system was analyzed using electrochemical methods under different magnetic field strengths. Nickel structures with aspect ratios of 7.0 and 8.2 were fabricated using the experimental setup, and their morphology, crystal texture, and microstructure were characterized. The results showed that without applying a magnetic field, the nucleation mechanism followed three-dimensional instantaneous nucleation under diffusion control. Under magnetic field conditions, forced convection, double layer charging, and hydrogen evolution reactions were combined to modify the S-H nucleation model, demonstrating that the magnetic field can significantly enhance the nucleation rate and number of nuclei. The initial growth of the microstructure did not exhibit preferential solid orientation, primarily forming refined equiaxed grains. Subsequently, a characteristic pentagonal structure developed, followed by spiral dislocation growth, with a significant transformation of equiaxed grains into columnar crystals. The crystal orientation eventually evolved to <110>, with many twin boundaries, among which Σ3 grain boundaries accounted for more than 55 %. Applying a magnetic field improved processing efficiency, altered the morphology and texture of the material, refined the grains, and increased the types of twins. These results provide theoretical and experimental support for electrochemical additive manufacturing.

Association between twin status with cognitive, behavioral development and brain structure in early adolescence: a retrospective cohort analysis based on the Adolescent Brain Cognitive Development Study.

Twin births are related with maternal and fetal adverse outcomes. Little was known about the comparability of the cognitive, behavioral development and brain structure between twins and singletons in early adolescence. This retrospective cohort study was based on data from the United States population-based, prospective, longitudinal observational Adolescent Brain Cognitive Development study. Children with complete twin status information were enrolled, and the exposure variable was twin status. Primary outcomes were cognitive, behavioral development and brain structure in early adolescence. Cognitive and behavioral outcomes were assessed by using the NIH Toolbox and Child Behavioral Checklist, respectively. Brain structure was evaluated by the cortical thickness, area, and volume extracted from the magnetic resonance imaging (MRI) data. Subgroup analyses were conducted by prematurity, birth weight, with sibling, genetic profiles, and twin types (zygosity). From 1st September 2016 to 15th November 2018, 11545 children (9477 singletons and 2068 twins) aged 9-10years were enrolled. Twins showed mildly lower cognitive performance (|t|> 5.104, P-values < 0.001, False Discovery Rate [FDR] < 0.001), better behavioral outcome (|t|> 2.441, P-values < 0.015, FDR < 0.042), such as lower scores for multiple psychiatric disorders and behavioral issues, and smaller cortical volume (t = - 3.854, P-values < 0.001, FDR < 0.001) and cortical area (t = - 3.872, P-values < 0.001, FDR < 0.001). The observed differences still held when stratified for prematurity, birth weight, presence of siblings, genetic profiles, and twin types (zygosity). Furthermore, analyses on the two-year follow-up data showed consistent results with baseline data. Twin status is associated with lower cognitive and better behavioral development in early adolescence accompanied by altered brain structure. Clinicians should be aware of the possible difference when generalizing results from adolescent twin samples to singletons.

Digital Twin—A Review of the Evolution from Concept to Technology and Its Analytical Perspectives on Applications in Various Fields

Digital Twin (DT) technology has experienced substantial advancements and extensive adoption across various industries, aiming to enhance operational efficiency and effectiveness. Defined as virtual replicas of physical objects, systems, or processes, Digital Twins enable real-time simulation, monitoring, and analysis of real-world behavior. This comprehensive review delves into the evolution of DT technology, tracing its journey from conceptual origins to contemporary technological implementations. The review provides detailed definitions, a classification of different types of Digital Twins, and a comparative analysis of their architectures. Furthermore, it investigates the application of DT technology in diverse sectors, with a particular emphasis on medicine and manufacturing, exemplified by use cases such as personalized medicine. Moreover, the review highlights emerging trends and future directions in DT technology, underscoring the transformative potential of integrating artificial intelligence and machine learning to augment DT capabilities. This analysis not only elucidates the current state of DT technology but also anticipates its future trajectory and impact across multiple domains.

Peripherally Inserted Central Venous Catheter (PICC) Line Use for Conjoined Twins: Single-Center Experience

Abstract Purpose This article assesses the feasibility, safety, and efficacy of peripherally inserted central catheters (PICCs) in conjoined twins. Material and Methods A retrospective chart review of all consecutive conjoined twins who had PICC placement at a tertiary center. Seventeen conjoined twins (12 females; 71%) had 25 PICC insertions. The average age of patients at PICC insertion was 15.9 ± 19.3 months. The most common type of twin was thoraco-omphalopagus (5 patients; 29%). The most common access was the brachial vein (N = 10, 40%). Thirteen procedures (52%) were performed before separation. Results Seven long-term minor complications were identified (28%). The most common complication was malpositioning (8%). Average dwell time was 122 days while the average fluoroscopy time was 2 minutes and 3 seconds. Conclusion Image-guided PICC placement in conjoined twins is safe and feasible. It provides excellent durable vascular access.

Comparison of Fetal Crown-Rump Length Measurements between Thawed and Fresh Embryo Transfer.

Background and Objectives: Neonates born from thawed embryo transfers tend to have a significantly higher birthweight compared to those from fresh embryo transfers. The aim of this study was to compare the crown-rump length (CRL) between thawed and fresh embryos to investigate the potential causes of different growth patterns between them. Materials and Methods: This was a retrospective study (July 2010-December 2023) conducted at the Third Department of Obstetrics and Gynecology, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Greece. In total, 3082 assisted reproductive technology (ART) pregnancies (4044 embryos) underwent a routine scan at 11+0-13+6 gestational weeks and were included in the study. Maternal age, the type of embryo transfer (thawed vs. fresh, donor vs. their own oocytes), CRL, twin and singleton gestations were analyzed. Results: The mean maternal age in thawed was significantly higher than in fresh embryos (39.8 vs. 35.8 years, p-value < 0.001). The mean CRL z-score was significantly higher in thawed compared to fresh embryo transfers (0.309 vs. 0.199, p-value < 0.001). A subgroup analysis on singleton gestations showed that the mean CRL z-score was higher in thawed blastocysts compared to fresh (0.327 vs. 0.215, p-value < 0.001). Accordingly, an analysis on twins revealed that the mean CRL z-score was higher in thawed blastocysts (0.285 vs. 0.184, p-value: 0.015) and in oocytes' recipients compared to own oocytes' cases (0.431 vs. 0.191, p-value: 0.002). Conclusions: The difference in CRL measurements between thawed and fresh embryos may be a first indication of the subsequent difference in sonographically estimated fetal weight and birthweight. This finding highlights the need for additional research into the underlying causes, including maternal factors and the culture media used.

Effects of Ti content on the tensile ductility, lattice distortion and mechanical properties of VNbTaTix refractory high-entropy alloys

Refractory high-entropy alloys (RHEAs) have remarkable properties like high strength and thermal stability at high temperatures. Their practical application is hindered by ambient brittleness and inferior formability. Titanium (Ti) is recognized as a crucial element in improving the ductility and oxidation resistance of RHEAs, but its plasticizing mechanism is still unclear. To address this, a series of body-centered cubic (BCC) single-phase VNbTaTix alloys were designed. The alloys exhibited exceptional ductility and cold-rolling formability at room temperature. Remarkably, the tensile fracture elongation of VNbTaTi alloy was about 26.9%, which surpassed most RHEAs. The major plastic mechanisms of the alloys are a/2<1 1 1>-type dislocation and {1 1 2}<1 1 1>-type twinning. Solid solution strengthening was identified as the primary strengthening mechanism. Although Ti reduced the solid solution strengthening effect, it contributed to weight reduction and enhanced local lattice distortion. This study not only designed several RHEAs with ductility but also provided insights into the effect of Ti content on their phase stability, lattice distortion, and strength mechanisms. These findings have significant implications for designing new RHEAs with ambient ductility.

Towards Understanding {10-11}-{10-12} Secondary Twinning Behaviors in AZ31 Magnesium Alloy during Fatigue Deformation.

Tensile-compression fatigue deformation tests were conducted on AZ31 magnesium alloy at room temperature. Electron backscatter diffraction (EBSD) scanning electron microscopy was used to scan the microstructure near the fatigue fracture surface. It was found that lamellar {10-11}-{10-12} secondary twins (STs) appeared inside primary {10-11} contraction twins (CTs), with a morphology similar to the previously discovered {10-12}-{10-12} STs. However, through detailed misorientation calibration, it was determined that this type of secondary twin is {10-11}-{10-12} ST. Through calculation and analysis, it was found that the matrix was under compressive stress in the normal direction (ND) during fatigue deformation, which was beneficial for the activation of primary {10-11} CTs. The local strain accommodation was evaluated based on the geometric compatibility parameter (m') combined with the Schmid factor (SF) of the slip system, leading us to propose and discuss the possible formation mechanism of this secondary twin. The analysis results indicate that when the local strain caused by basal slip at the twin boundaries cannot be well transmitted, {10-11}-{10-12} STs are activated to coordinate the strain, and different loading directions lead to different formation mechanisms. Moreover, from the microstructure characterization near the entire fracture surface, we surmise that the presence of such secondary twins is not common.

Second twin outcome at birth: retrospective analysis in a single tertiary centre in Malaysia.

To investigate factors associated with outcome of second twin during labour. The study was a retrospective cohort study in a single tertiary centre in Malaysia from 2014 until 2018 involving all twin pregnancies delivered at or more than 24weeks of gestation. Total of 409 twin pregnancies were included. Dichorionic twin comprises of 54.5 % (n=223) and 45.5 % (n=186) are monochorionic. Women with dichorionic pregnancies are significantly older (p<0.001), have more pre-existing medical disorders (p=0.011) and fetal structural anomalies (p=0.009). Monochorionic pregnancies are significantly more amongst Malay (p=0.01) and conceived spontaneously (p<0.001). There are significantly more fetuses both in cephalic presentation (p=0.026), birthweight discrepancy more than 20 % (p=0.038) and shorter mean inter-twin delivery duration (p=0.048) in monochorionic pregnancies. Second twin delivered with Apgar score <7 is significantly more in dichorionic pregnancies (p=0.006). The second twin is associated with lower birthweight, small for gestational age and arterial cord pH<7.25. Within the group of women who delivered both fetuses vaginally, there was significantly more second twins with intertwin delivery duration less than 30 min who were delivered vaginally without instrumentation (p=0.018). There was significantly more second twin with intertwin delivery duration of 30 min and more with arterial cord pH<7.25 (p=0.045). Those who delivered spontaneously had inter-twin delivery duration within 15-29 min. The outcome of second twin is not influenced by type of twin, gestational age at delivery, inter-twin delivery duration, mode of delivery and presentation at birth. The neonatal outcome for the second twin at birth is not influenced by type of twin, gestational age at delivery, inter-twin delivery duration, mode of delivery and presentation at birth in a cohort managed with non-active management of the second twin in Malaysia.

The effect of parity on time to initiate complementary feeding among mother-infant pairs in Awi Zone, Northwest Ethiopia

IntroductionDespite strategies and recommendations for complementary feeding initiation were applied globally, mothers initiated complementary feeding to the infants on time was low. Previous works of literatures were not identified the effect of parity on time to initiate complementary feeding. Particularly, evidences regarding to this in Ethiopia is scanty. Therefore, this study aimed to identify the effect of parity on time to initiate complementary feeding among mother-infants pairs in Northwest Ethiopia.MethodsA community-based prospective cohort study was carried out among 732 primipara, and 1464 multipara mothers who had a live birth in Northwest Ethiopia. Data were collected using Kobo collect software at the start of and on a monthly bases until the end of the follow up period. Parity as exposure variable and other confounders were analyzed using cox proportional hazard regression. Kaplan-Meier survival curve and the Schoenfeld residuals global test (P-value = 0.4861) was performed. Hazard ratio (HR) with 95% confidence intervals (CI) was used to declare statistical significance of predictors.ResultsThe overall incidence rate of initiation of complementary feeding among primipara and multipara mothers were 16.27 (95%CI: 15.04, 17.61) and 13.30 (95%CI: 12.53, 14.12) person months’ observations respectively. The median time to initiate complementary feeding among primipara and multipara mothers for their infants was 5 and 6 months respectively. Primipara mothers had a 30% higher rate to initiate complementary feeding early (AHR = 1.30, 95%CI: 1.17, 1.43). Age from 15 to 24 and 25–34 years (AHR = 1.69, 95%CI: 1.36, 2.09; and AHR = 1.45, 95%CI: 1.17, 1.81) and Birth type (twin) (AHR = 1.29, 95%CI: 1.02, 1.64) were statistically significant predictors for time to initiate complementary feeding.ConclusionsParity was identified as a statistically significant predictor for time to initiate complementary feeding. The incidence rate of early and late initiation of complementary feeding was higher among primipara than multipara mothers. Besides, the median time to initiate complementary feeding was earlier among primipara than multipara mothers. So, a parity based complementary feeding practice education should be advocated to tackle the gap and further reduce infants and children malnutrition. Relatively younger age and twin delivered mothers initiated complementary feeding against the recommendation. Therefore, intervention considering such statistically significant predictors could have a public health importance.

Digital Twins along the product lifecycle: A systematic literature review of applications in manufacturing

Background The evolution of product expectations in the era of mass personalization implies an improvement and a better control of individualized creation and production processes throughout the product lifecycle. The application of the digital twin seems to be a favoured solution in this context, but its study during the lifecycle of a product has only been partially evoked in the literature. Methods The purpose of this research is to identify the leverages and barriers to support the digital twin diffusion in the manufacturing industry from a technological, operational, and social standpoint. To determine these elements, this paper will identify current digital twins applications in the literature under two main dimensions: the type of digital twin, and its applications along the product lifecycle. To achieve this analysis a systematic literature review was carried out. The publications selection was based on the presence in these of a case of application of a digital twin with a focus in the Manufacturing sector. Within this review, 188 scientific papers were comprehensively compiled and analyzed. Results Results showed that although the term digital twin is widely used, the deployment of digital twin technologies in manufacturing is still at an early stage as most of the reported digital twin applications were in fact prototypes focused on the real-time observability of the physical system, either for optimization or predictive maintenance. Moreover, regarding the product lifecycle, most of the applications have been focused on the production and operational phases whereas those at the design and disposal phases are still limited. Conclusions This paper presents an original approach to the study of digital twins, focusing simultaneously on the type of digital twin, the application area and the lifecycle phase. Under the basis of the obtained results, future perspectives on the use of digital twins along the lifecycle are proposed.